Several thousand years ago, Africa was considerably wetter than in recent years. This period, called the African Humid Period, lasted from roughly 14,000 to 5,000 years ago, was related to higher temperatures and more greenhouse gases, according to an article in Bloomberg Businessweek. Recent simulations of climate for that time period match the climate determined from pollen, tree rings, and other proxy data and give climate modelers confidence that they are on the right track with simulating future climate patterns. One of the trends they expect is an increase in rainfall in parts of Africa near the Sahara and Sahel, and observations show that vegetation is expanding in these areas. This may make some parts of Africa more favorable for agriculture in the future, which will be a boon to people living in those areas. However, it is not certain how much the rainfall will increase, and if it increases too much, erosion and other problems could also surface. Another article on this subject is on the UPI website.